The ‘best part’ of David Cone’s perfect game commemoration

Now that the 20th anniversary of David Cone’s perfect game against the Expos on July 18, 1999, has passed, there wasn’t much left for the retired right-hander to reveal about his accomplishment — even as the Yankees honored him Thursday with David Cone Bobblehead Night. At an over-the-top charity party on June 19 at Manhattan’s…